SERVICES DAY04 （05）：使用systemctl工具

5.1 问题
本例要求掌握systemctl控制工具的基本操作，完成下列任务：

1. 重启 httpd、crond、bluetooth 服务，查看状态
2. 禁止 bluetooth 服务开机自启，并停用此服务
3. 设置默认级别为 multi-user.target 并确认
   5.2 方案
4. [root@svr7 ~]# journalctl -u httpd
5. – Logs begin at Thu 2017-01-05 15:50:08 CST, end at Fri 2017-01-06 18:01:01 CST.
6. Jan 06 14:57:16 svr7 systemd[1]: Starting The Apache HTTP Server…
7. Jan 06 14:57:16 svr7 httpd[23812]: AH00557: httpd: apr_sockaddr_info_get() failed for
8. Jan 06 14:57:16 svr7 httpd[23812]: AH00558: httpd: Could not reliably determine the server
9. Jan 06 14:57:16 svr7 systemd[1]: Started The Apache HTTP Server.
10. Jan 06 17:53:44 svr7 systemd[1]: Stopping The Apache HTTP Server…
11. Jan 06 17:53:46 svr7 systemd[1]: Starting The Apache HTTP Server…
12. Jan 06 17:53:46 svr7 httpd[33741]: AH00557: httpd: apr_sockaddr_info_get() failed for svr7
13. … …
14. [root@svr7 ~]# journalctl --since “2017-01-06 14:11” --until “2017-01-0